A bolstered police presence and miles of barriers and bulletproof glass are certain to catch everyone’s eye, which is why the D.C. Department of Transportation is warning commuters to expect extreme gridlock – starting with a citywide suspension of construction-related commercial deliveries.

If it pours concrete, delivers supplies, or hauls debris, it’s halted until midnight on Wednesday. And the news is catching crews by surprise on Tuesday night.

"I have a couple of port-a-potties that I have to deliver to First Street," said delivery driver Jason Kramer.

There will be roadblocks throughout Ward 2 and Ward 6, as all road work and non-emergency commercial traffic is suspended through midnight on Wednesday.

And federal workers also need to be on alert, as the Office of Personnel Management expects all agencies to be open but is recommending an alternative work schedule day off or annual leave day. Meanwhile, government workers are encouraged to telework on Wednesday due to the commute.

Almost every major road and side street feeding the Mall will be shut down from 4 a.m. to 4 p.m., as thousands of people are expected to flood the National Mall.

President Barack Obama and former presidents Bill Clinton and Jimmy Carter will speak at the event at about 1 p.m. If you’re heading to the event, you are strongly advised to use public transportation. Metro stations near the National Mall and Memorial Parks, U.S. Capitol, and President's Park will remain open through the day.

Ticketed participants with mobility issues can take advantage of a free shuttle offered from the Foggy Bottom Metro into the event. DDOT officials say that riders should avoid the Arlington Cemetery, Smithsonian and Federal Triangle stations; the Memorial Bridge will be closed to foot traffic and the two others are subject to major crowding.

Starting at 4 a.m., The National Park Service will close the following monument sites through 4 p.m.

Lincoln Memorial

Vietnam Veterans Memorial

Korean War Veterans Memorial

World War II Memorial

District of Columbia War Memorial

The following streets close at 3 a.m. and are scheduled to reopen by 6:30 p.m.:

Westbound ramp from I-395 to Maine Avenue SW; all traffic will be diverted to the 12th Street Tunnel

Ramp from 9th Street tunnel to westbound Maine Avenue Southwest; all traffic will be diverted to outbound I-395

200 block of Maiden Lane at the merge with Maine Avenue SW; all traffic will be diverted to northbound 14th Street Southwest

Southbound Potomac River Freeway and ramp to Independence Avenue; traffic will be diverted to the outbound Theodore Roosevelt Bridge